It is known to provide the tube plates of condensers, coolers, or heat exchangers with a coating of plastic material in order to protect them against corrosion. For this purpose it is necessary to expose the tube plates or the like, if this has not already been done, to enlarge the ends of the tubes imbedded therein, and to close their ends by means of plugs made of synthetic material. Around these plastic plugs, a sealing liquid is applied to the tube plates. The seal is suitable to prevent formation of corrosion craters around the tube ends of either new or already used tube plates. After these operations are completed, the anti-corrosion medium is applied by hand like a primer mass, all the way over the corks in order to insure a complete coating. After the anti-corrosion medium has hardened, it is removed by grinding in the area of the corks, so that these can be removed individually. The application of coatings of anti-corrosion medium to tube plates or the like has proven to be the best known method. Unfortunately, the method is comparatively cumbersome, and thus very expensive, to perform.